Solar concentrators operate by focusing light to a spot on a photovoltaic cell. The concentrated spot of light enables a small semiconductor to operate at higher power density levels than would be possible in flat solar panels without optical concentration. By using optical concentration, it is possible to construct a photovoltaic system using less semiconductor material, thus desirably lowering production costs.
As a result of optical concentration, the photovoltaic cell produces electric power at high current and with a significant heat load. Thus, measures must be employed to thermally shield the electrical connections and other sensitive components surrounding the photovoltaic cell from the focused light beam. Provisions must also be made to remove the heat load, for which a heat sink is commonly employed.
In order to allow the series connection of concentrated photovoltaic devices (which is often desired), the semiconductor materials of the cells must be electrically insulated from the heat sink materials and from each other. Electrically insulating the cells from the heat sink also allows operators to handle the devices without risk of electric shock. This electrical insulation is usually accomplished by attaching each photovoltaic cell to a ceramic or composite plastic substrate on which top surface metal connection pads are provided.
Standard connectors and cables exist for external connections that are capable of carrying both high current and high voltage direct current (DC) electricity to/from the photovoltaic cells. It is often necessary to make connections using these standard connectors (which are often physically large) to the photovoltaic cell directly or indirectly via conductors on the photovoltaic cell substrate. One method used in the field is to solder both pin and socket connectors directly on the package (the package in this case being the substrate on which the photovoltaic cell is mechanically and electrically affixed). However, the substrate is often made up of thin layers of ceramic and this practice imposes considerable strain on the substrate material and any conductive and insulating coatings that may have been applied to the substrate. In addition this method may restrict the number of contact points through which a large amount of current will be passed.
The components used to construct concentrated solar receivers having a solar cell, cell package (or substrate) and in some cases a heat sink are expensive. It is desirable for cost reasons to be able to remove and rework these assemblies. It is also desirable to be able to re-work or replace receiver components in the field. To this end it is desirable to avoid soldering and other complex process operations.
Therefore, techniques for providing high-capacity, field re-workable connections in concentrated photovoltaic devices would be desirable.